Thetford Cassette Toilet C500 flush stopped working

[Abgs]

My toilet has stopped flushing. The green light on the flush button doesn’t light up.

The only thing I’ve tried so far is swapping the cassette for my new spare one, but, no joy.

I’ve watched a Youtube video on how to dismantle it and get at the internals and am quite confident that I could that.

But before I do that … does anyone know where I should start my trouble shooting? Does the toilet have a dedicated fuse and where might that be in a Hymer Exsis-I?

The internals look like this … thetford-cassette-toilets-c500

Any pointers appreciated!

 

[XxAnthxX]

Oh no...that’s sh*t.

 

[Swifter]

Is there a fuse inside the cassette hatch ?

 

[Abgs]

Is there a fuse inside the cassette hatch ?

I'll have look tomorrow and see what I can see.

 

[Marmite]

Alternatively, possible switch failure. Had to replace mine in the Caravan 2 years ago.

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[Abgs]

Still not fixed this ... have been using the watering can method to flush in the mean-time.

I can't find a fuse anywhere so I emailed Thetford with the serial number to ask where it might be.

They replied that the unit was still under warranty so its going in next week to be looked at.

 

[grumfy]

My toilet has stopped flushing. The green light on the flush button doesn’t light up.

That is interesting, my less than 3 months old C500 system is playing up in the same way too. However, if I remove the cassette and refit it sometimes it starts to work again for a while. I thought maybe the magnet that the electronics sense on the float may have gone awol. But I had the top off and all is ok there. I have not found a fuse but under a plate on the left side I found the electronics pcb. Took that out and it looked ok to the untrained eye. Put it back in but still no difference.
And so I am interested to know how it turns out for you.

 

[Pete5996]

Don't rule out the possibility of an air lock in the water supply. Happened to my C250 last week when I was filling the system. Flush didn't operate until the airlock was cleared.

 

[Phileas Dog]

Had a similar problem earlier this year, the fuse had gone, it was the one situated in the flush button system
iThe whole press button control will lift out, there is a fuse inside, well there was in ours, new fuse solved the problem.

 

[Abgs]

That is interesting, my less than 3 months old C500 system is playing up in the same way too. However, if I remove the cassette and refit it sometimes it starts to work again for a while. I thought maybe the magnet that the electronics sense on the float may have gone awol. But I had the top off and all is ok there. I have not found a fuse but under a plate on the left side I found the electronics pcb. Took that out and it looked ok to the untrained eye. Put it back in but still no difference.
And so I am interested to know how it turns out for you.

My dealer appointment has been pushed back to Nov 10th so I'm going to have another look. I'll update this post with pictures and anything I find out.

Don't rule out the possibility of an air lock in the water supply. Happened to my C250 last week when I was filling the system. Flush didn't operate until the airlock was cleared.

Mine is a C500L doesn't have a pump as such it uses the main pump from the water tank and a Solenoid valve - as far as I understand. There is water at the solenoid but no power to fire it up.

Had a similar problem earlier this year, the fuse had gone, it was the one situated in the flush button system
iThe whole press button control will lift out, there is a fuse inside, well there was in ours, new fuse solved the problem.

Ahh ... I did lift the switch assembly off but couldn't see anything obvious. Looking at the attached parts diagram item 27 seems to go from the switch to the PCB board. It looks like there may be a fuse in the lead. I'll check it later this week. Hopefully that's it. I'd rather know how it works and be able to fix it myself than take it to the dealer.

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[Abgs]

That is interesting, my less than 3 months old C500 system is playing up in the same way too. However, if I remove the cassette and refit it sometimes it starts to work again for a while. I thought maybe the magnet that the electronics sense on the float may have gone awol. But I had the top off and all is ok there. I have not found a fuse but under a plate on the left side I found the electronics pcb. Took that out and it looked ok to the untrained eye. Put it back in but still no difference.
And so I am interested to know how it turns out for you.

Right ...fixed it!

After spending an hour or so dismantling it to try and find a fuse I couldn't find one anywhere.

It comes apart like this:



I also took the cassette apart to check the level indicator mechanism. I'm not quite sure how it works - there is a magnet is the float arm which must do something.

But anyway, I didn't need to do any of that.... The problem was the push button switch.

The button / cover is stuck to the PC board. It's possible to carefully unstick the two items. As soon as I did I realised the switch contacts needed cleaning. They had gone a greenish cover. Quick clean with fine sandpaper, and cover stuck back to the PC board and the flush started to work again.

However the green and red level lights are not showing. Not the end of the world but I'm going to order a new switch assembly (about £30) and 5 minute job to fit.

Hope the above might help someone.